The prior art can best be explained by discussing specific United States patents.
U.S. Pat. No. 3,616,961 teaches a can-like container having a tear strip in the end panel which is unfolded by pulling a pull member. Beads on the end panel provide rigidity where required so that further pulling of the tear strip causes it to bend into a pitcher type pouring lip.
U.S. Pat. No. 3,473,705 teaches a tear strip with a pull tab. The tear strip defines an opening, and as the strip is further pulled, a pour spout is formed by pulling a bendable sheet from the interior of the container through the opening.
U.S. Pat. No. 3,216,609 teaches a container with a tear strip wherein a concealed pre-fabricated spout member is pulled out of the container by pulling the tear strip. The spout has stops on it to prevent full removal from the container.
Unfortunately the latter two spouts are not sealed at their side edges when the spout is open, whereby there is a liklihood of fluid leakage around the spout structure edges.